Filtered feedthrough assembly for implantable medical electronic devices

Abstract

A filtered feedthrough assembly for an implantable medical device comprises a ferrule, an electrical insulator coupled to the ferrule by a connection element, a plurality of feedthrough conductors extending through the electrical insulator, a printed circuit board (PCB), and plurality of capacitors. The PCB is coupled to the ferrule or the electrical insulator, and includes one or more ground layers and a plurality of vias. The connection element is electrically coupled to the ground layer through the vias. The capacitor has a ground terminal electrically coupled to the ground layer through at least one of the vias, and a conductor terminal electrically coupled to the feedthrough conductor.

We claim: 
     
       1. A filtered feedthrough assembly for an implantable medical device, comprising:
 a ferrule configured to be connected to a metal case of the implantable medical device; 
 a printed circuit board (PCB) coupled to the ferrule, wherein the PCB includes a plurality of ground layers and a plurality of vias in electrical contact with the plurality of ground layers; 
 an electrical insulator coupled to the ferrule by a connection element, wherein the connection element is electrically conductive and is electrically coupled to the ferrule and the ground layers of the PCB through the vias; 
 a feedthrough conductor extending from outside the metal case to inside the metal case and extending through at least one ground layer of the plurality of ground layers of the PCB electrically coupled to the connection element; and 
 a filter circuit electrically coupled to the feedthrough conductor and electrically coupled to the at least one ground layer of the PCB through at least one of the vias. 
 
     
     
       2. The filtered feedthrough assembly of  claim 1 , wherein the connection element is a braze of conductive metal. 
     
     
       3. The filtered feedthrough of  claim 2 , wherein the conductive metal includes one or both of gold and silver. 
     
     
       4. The filtered feedthrough of  claim 1 , wherein the connection element includes conductive metal soldered to the ferrule and the electrical insulator to form a hermetic seal. 
     
     
       5. The filtered feedthrough assembly of  claim 1 , wherein the filter circuit includes a capacitor having a ground terminal electrically coupled to the ground layer through at least one of the vias, and a conductor terminal electrically coupled to the feedthrough conductor. 
     
     
       6. The filtered feedthrough assembly of  claim 1 , wherein the vias provide multiple electrical paths from the connection element to the ground layer of the PCB. 
     
     
       7. The filtered feedthrough assembly of  claim 1 , further comprising a conductive epoxy disposed within at least one of the vias to electrically couple the connection element to the ground layer. 
     
     
       8. The filtered feedthrough assembly of  claim 1 , wherein the plurality of vias traverse the plurality of ground layers. 
     
     
       9. The filtered feedthrough assembly of  claim 1 , further comprising a plurality of feedthrough conductors extending through the electrical insulator, and a plurality of filter circuits coupled to the feedthrough conductors, wherein the plurality of filter circuits include a plurality of capacitors, each capacitor of the plurality of capacitors associated with one of the plurality of feedthrough conductors. 
     
     
       10. The filtered feedthrough assembly of  claim 9 , wherein each capacitor of the plurality of capacitors includes a ground terminal electrically coupled to the plurality of ground layers by at least one of the vias, and a conductor terminal electrically coupled to a respective one of the feedthrough conductors. 
     
     
       11. An implantable medical device comprising:
 a metallic housing; 
 a ferrule connected to the metallic housing; 
 a printed circuit board (PCB) coupled to the ferrule, wherein the PCB includes a plurality of ground layers, and a plurality of vias traversing the ground layers; 
 a connection element electrically coupled to the ferrule and the ground layers of the PCB through the vias; 
 a feedthrough conductor extending from outside the metallic housing case to inside the metallic housing and extending through at least one ground layer of the plurality of ground layers of the PCB electrically coupled to the connection element; and 
 a filter circuit electrically coupled to the feedthrough conductor and electrically coupled to the ground layer of the PCB through at least one of the vias. 
 
     
     
       12. The implantable medical device of  claim 11 , including an electrical insulator arranged around the feedthrough conductor, and wherein the connection element is a gold braze material disposed so as to attach the electrical insulator to the ferrule. 
     
     
       13. The implantable medical device of  claim 11 , wherein a conductive epoxy is disposed within the plurality of vias so as to electrically couple the electrically conductive connection element to the plurality of ground layers. 
     
     
       14. The implantable medical device of  claim 11 , wherein the electrically conductive connection element is a gold braze material, and wherein conductive epoxy is disposed within at least one of the plurality of vias to contact the gold braze material so as to provide a plurality of electrical paths electrically coupling the gold braze material to the plurality of ground layers. 
     
     
       15. The implantable medical device of  claim 11 , further comprising at least one ground pin electrically coupled to the plurality of ground layers, wherein the at least one ground pin is coupled to the plurality of ground layers by a conductive epoxy injected into at least one of the plurality of vias. 
     
     
       16. The implantable medical device of  claim 11 , further comprising a plurality of ground pins electrically coupled to the plurality of ground layers. 
     
     
       17. A method of making a filtered feedthrough assembly for an implantable medical device, the method comprising:
 providing a PCB having a plurality of ground layers and a plurality of vias extending through the ground layers; 
 disposing a plurality of filter circuits on the PCB, wherein a filter circuit is electrically coupled to the plurality of ground layers through at least one of the vias; 
 arranging a plurality of feedthrough conductors to pass through a ferrule, and each pass through an electrical insulator and through the plurality of ground layers of the PCB, wherein the electrical insulator is coupled to the ferrule by an electrically conductive connection element; 
 electrically coupling each of the feedthrough conductors to a filter circuit; and 
 electrically coupling the connection element to the plurality of ground layers of the PCB using the vias, wherein the feedthrough conductors extend through the ground layers of the PCB electrically coupled to the connection element. 
 
     
     
       18. The method of  claim 17 , including brazing the electrical insulator to the ferrule to form the electrically conductive connection element. 
     
     
       19. The method of  claim 18 , wherein brazing the electrical insulator to the ferrule includes brazing the electrical insulator to the ferrule using gold. 
     
     
       20. The method of  claim 17 , including disposing a conductive material in the plurality of vias so as to contact the connection element of the ferrule and provide a plurality of parallel electrical paths from the connection element of each of the ferrules to the plurality of ground layers.